Apparatus for driving a sheath at variable and automatically adjustable speed in a machine for making plastic bags

ABSTRACT

This invention relates to a device for driving a sheath at variable and automatically adjustable speed, characterized in that the members for controlling the speed of the two motor speed regulators are connected respectively by a transmission to two shafts on which are keyed two planetary pinions of a differential, the cage of which carrying the satellite pinions may be rotated during the displacement of a set of free rollers on which the sheath is wound.

"r 1 1.1 1 1 t 11.] 1151 31 Lagmfim; FM? E iig i y [54] APWARAWUfi WEBER DFERHWKNG A MKEATFH 3,087,663 4/1963 Andemon 2215/ 1 1- ALT lfitiiiiiliiifiiiilifl AND IMJ'iiQMA'iFIiQALLY 11111111111111.1111 when 1111 11 MAMJHHNE FOREKGN PATENTS OR WWQWUM MAMHNG ii ihfii 'iiiitj iiilififi 1,102,885 3/1961 Germany 226/ 14- [72] Envemm: gijg fifi gjff 3 rue des Sol-blew 95 Er. Primary Examine1'1tichard A. Sehacher A1torney-ioh1n Lezdey [22} Filed: Maw 15, 11%7111 [21] 11 1 31110.: ii'htflfi [57] Aim'iiimtl'ii This invention relates to a device for driving 11 shenth mt wrin- [30] Foreign mn giiientim Priority 1111mm ble and automaticaily ndjustahie speed, characterized 111 that Ma 20 1969 Frame 6916303 the members for conti'oiiing the speed of the two motor speed y regulators are connected respectively by a transmission to two 52 115.1121! me/1n, 226/44, 226/111 Shafts which W Planetary Pinion? a 51 11m UM 51;, 23 2 iferential, the cage of which carrying the satellite pinions may 58 inane 111 swim ..226/40, 4 1-, 111,311,31 be rotated during the displacement of a set of free wllm 011 which the sheath is wound.

[56] iiieierenees Cited 1 (115111115, 11 Drawing i iguii'e UNiTED STATES PATENTS 1 2,151,570 3/1939 tim ng 'l he present invention relates to an apparatus for driving a sheath at variable and automatically adjustable speed in a machine for making plastic bags.

For manufacturing plastic bags, it is known to use machines in which a predetermined length of sheath is made to advance, which is cut and welded on one of its edges to form a bag.

The sheath, which is unwound from a storage reel, is driven by a first pair of rotary rollers followed by an assembly of fixed and movable rollers of conventional type on which the sheath is wound, and by a second pair of rotary rollers arranged upstream of the welding and cutting jaws, according to the direction of advance of the sheath.

However, this ltnown driving device does not enable a regular advance of the sheath and a constant pulling from the beginning to the end of the reel to be obtained, so that irregularities in the length of the bags result.

in accordance with the present invention, a device for driving a sheath at variable and automatically adjustable speed is used in a machine for manufacturing plastic bags, in which the sheath driving device comprises, following a reel around which the sheath is wound, a first pair of drive rollers, a series of tired and movable, freely rotating rollers, and a second pair of drive rollers, each pair of drive rollers being actuated by a motor speed regulator, characterized in that the members for controlling the speed of the two motor speed regulators are respectively connected by a transmission to two shafts on which are keyed two planetary pinions of a differential, the cage of which carrying the satellite pinions may be rotated during the displacement of a set of free rollers on which the sheath is wound.

The device according to the invention enables the sheath to be advanced in regular manner, i.e., withoutjerlt's, and enables very heavy sheaths to be used in the machine.

On the other hand, it eliminates the adjustments of the conventional assembly of fixed and movable rollers and procures a constant pulling from the beginning to the end of the reel, this resulting in a regularity in the manufacture of the bags.

The invention will be described in greater detail with reference to the accompanying drawings, in which:

The single FlGURlE shows a schematic elevational view of an embodiment of the drive device according to the invention.

in the drive device according to the invention, shown in the single HGURE, the sheath ll coming from a storage reel 2 is engaged between a first pair of rollers 3, 3a, at least one of which, 33a, is driven by a motor speed regulator l by means of a transmission member 5.

After the rollers 3i, Zia there is arranged an assembly of fixed and movable rollers on which is wound the sheath and comprising frce rollers ii, the, st, mounted in bearings fixed to the frame of the machine and movable free rollers 2, 2a, capable of moving with respect to the frame of the machine.

On leaving the roller rib, the sheath l is directed between a second pair of rollers ll, be, only one of which, fizz, is connected by a transmission member 9 to a motor speed regulator ill The members for controlling the speed of the motor speed regulator il are connected by a shaft ill and a transmission member l2 to a pulley l3 keyed to a shaft Ml carrying at one of its ends a handwheel l5 and at its other end a planetary pinion lid of a differential l7, said planetary pinion to being connected by satellite pinions to a planetary pinion l9 keyed to a shaft The planetary pinions lid, .lda mounted to rotate on axes 2i, Illa unitary with a cage .22 of the differential 117.

The shaft 2h, one of whose ends is unitary with the planetary pinion l9, carries at its other end a pinion 2.3 meshing with a revcrser pinion 2d unitary with a shaft on which is keyed a pulley 2d which, by means of a transmission 2'7, is connected to a shaft controlling the speed control members of the motor speed regulator d.

Furthermore, the rollers 7, 2a are mounted to rotate at each of their ends on a support member 29 fixed to an endless chain 3b, mounted on a pair oftoothed wheels Ell, Ella.

On the opposite side of the support member 29 a boss Jill is fixed to the other edge of one of the endless chains which boss may come into contact with two stop members Zid, 33 n unitary with an endless chain or belt 3 d arranged on a toothed wheel mounted to rotate on the frame: and on a toothed wheel 36 unitary with the cage 22 of the differential H2.

The drive device operates as follows:

The motor speed regulators 4i and. ill) are set into operation at the same time, but the rollers 3, Zia are only rotated if the rollers 8, be are themselves rotated.

To this end, a clutch is arranged between the motor speed regulator d and the rollers 3, 3n, as well as between the motor speed regulator lid and rollers it, do. The two clutches, which are preferably electromagnetic, are mounted in parallel and are actuated from a single control contactor.

For adjusting the speed of the rollers it, be and rollers El, when the machine starts operating, in order to increase or reduce their speed, the handwheel lid is maneuvered in order to rotate the shaft Ji l and the pulley or toothed wheel ill in one direction or the other and to act, by the transmission l2, on the rotation of the shaft lll. controlling the means for ad justing the motor speed regulator ill.

The planetary pinion l6 and pinions ill, lllla are used to rotate cage 22 and the endless chain lid is driven until one of the stop members 3%, 33a comes into contact with the boss 32.

Due to the resistant torque opposed by the assembly of fixed and movable rollers, the cage is fixed and the planetary pinion i6 drives pinion li by the satellite pinions lib, tile.

in this way, the shaft 2% is also driven which transmits its movement by the reverser pinions 23, 24 and the transmission 26, 27 to the shaft 23 for controlling the members for adjust-- ing the motor speed regulator.

The shaft 20 rotating in opposite direction to shaft l t, a pair of reverser pinions 23, 24 is arranged between the shaft 2% and shaft 23, so that the rotation of the handwheel lid in one direction ensures the same action in the sense of the increase or decrease in speed, on the means controlling the motor speed regulators l and ill.

During operation of the machine, when the speeds of the two regulators d and have been preadjusted, it is sufficient to modify the speed of the rollers 3, 35a by acting on the motor speed regulator, in order to increase its speed if the output of the rollers 8, do is different from that of rollers 3, 3a.

If the quantity of sheath delivered by rollers h, lla is greater than that delivered by the rollers Ell, 3n, the free rollers '7, hr and the support 29 rise, in the direction of arrow A so that the boss 32 comes into contact with the stop member 32in and drives the endless chain 3% in the direction of the arrow B, causing the pinion 3b and the cage 22 of the diifcrential to rotate about its axis.

As the pinion lid is tired and offers a resistant torque, the satellite pinions ill, llda drive the planetary pinion l9 and the shaft 243 which controls, by transmission 27, the drive of the shaft 28, in order to act on the means for adjusting the motor speed regulator t in order to increase the speed of the rollers 35, do.

As soon as the output of the rollers El, do is increased, the rollers 7, 7a descend in the direction opposite that of arrow A, until the speed is stabilized, in order to correspond to the normal output of the machine.

However, if the output of sheath of the rollers Fl, 3a is greater than that of rollers 8, ha of the machine, the rollers "1', 7a and the support l ll continue to descend in direction opposite that of arrow A, so that the boss 32 comes into contact with the stop member 33 and ensures the rotation of the cage 22 in opposite direction.

As previously, the satellites lltl, that drive the pinion W, the shaft 2i) and, by the transmission 27, the shaft 23 which con trols the members for adjusting the mot-or speed regulator d, in the sense of a reduction in speed or" the rollers 3, do.

As soon as the speed of the rollers 3, 3a is reduced, the rollers 7, 7a rise again in order to occupy a stable position.

Of course, the invention is not limited to the sole embodiment that has been described and shown, but covers on the contrary all the modifications that may be made thereto,

What is claimed is:

l. A device for driving a sheath at variable and automatically adjustable speed in a machine for manufacturing plastic bags, in which the sheath driving device comprises, a differential having a rotatable cage, a first pair of drive rollers, a series of fixed and movable freely rotatable rollers, and a second pair of drive rollers, each pair of drive rollers being actuated by a motor speed regulator, wherein the members for controlling the speed of the two motor speed regulators are respectively connected by a transmission to two shafts on which are keyed two planetary pinions on said differential, said cage of said differential carrying the satellite pinions and rotatable during the displacement of a set of free rollers on which the sheath is wound.

2. A device for driving a sheath at variable and automatically adjustable speed in a machine for manufacturing plastic bags, in which the sheath driving device comprises, a differential having a rotatable cage, a first pair of drive rollers, a series of fixed and movable freely rotatable rollers, said movable rollers being mounted on support means so as to permit their vertical displacement and having an actuator member capable of acting selectively during passage on two stop members fixed at a certain distance from one another on a linearly moving member connected to said cage of said differential, and a second pair of drive rollers, each pair of drive rollers being actuated by a motor speed regulator, wherein the members for controlling the speed of the two motor speed regulators are respectively connected by a transmission to two shafts on which are keyed two planetary pinions of said differential, said cage of said differential carrying the satellite pinions being rotatable during the displacement of a set of free rollers on which the sheath is wound.

3. A drive device as defined in claim 2, wherein the means for supporting the movable rollers comprise two endless chains mounted on two pairs of toothed wheels, two support members carried on one side of said chains in which the ends of said rollers are rotatably mounted, one of said chains carrying on the other side a boss capable of coming into contact with two stop members mounted on endless chain mounted on a pair of toothed wheels, one of said wheels being unitary with said cage of said differential.

4. A drive device as defined in claim 2, wherein a pair of movement reversing pinions is mounted between the shaft on which is keyed one of said planetary pinions and said transmission controlling one of said speed regulators.

Anna: 

1. A device for driving a sheath at variable and automatically adjustable speed in a machine for manufacturing plastic bags, in which the sheath driving device comprises, a differential having a rotatable cage, a first pair of drive rollers, a series of fixed and movable freely rotatable rollers, and a second pair of drive rollers, each pair of drive rollers being actuated by a motor speed regulator, wherein the members for controlling the speed of the two motor speed regulators are respectively connected by a transmission to two shafts on which are keyed two planetary pinions on said differential, said cage of said differential carrying the satellite pinions and rotatable during the displacement of a set of free rollers on which the sheath is wound.
 2. A device for driving a sheath at variable and automatically adjustable speed in a machine for manufacturing plastic bags, in which the sheath driving device comprises, a differential having a rotatable cage, a first pair of drive rollers, a series of fixed and movable freely rotatable rollers, said movable rollers being mounted on support means so as to permit their vertical displacement and having an actuator member capable of acting selectively during passage on two stop members fixed at a certain distance from one another on a linearly moving member connected to said cage of said differential, and a second pair of drive rollers, each pair of drive rollers being actuated by a motor speed regulator, wherein the members for controlling the speed of the two motor speed regulators are respectively connected by a transmission to two shafts on which are keyed two planetary pinions of said differential, said cage of said differential carrying the satellite pinions being rotatable during the displacement of a set of free rollers on which the sheath is wound.
 3. A drive device as defined in claim 2, wherein the means for supporting the movable rollers comprise two endless chains mounted on two pairs of toothed wheels, two support members carried on one side of said chains in which the ends of said rollers are rotatably mounted, one of said chains carrying on the other side a boss capable of coming into contact with two stop members mounted on endless chain mounted on a pair of toothed wheels, one of said wheels being unitary with said cage of said dIfferential.
 4. A drive device as defined in claim 2, wherein a pair of movement reversing pinions is mounted between the shaft on which is keyed one of said planetary pinions and said transmission controlling one of said speed regulators. 